I don't hit this limit often, but when you get the "you can only perform this action every 60 seconds" (what action?) like when posting a question, it just dumps you on a blank page with only that message (a la classic PHP die() "error pages"). This is pretty ugly and confusing. I think some Mod actions do it as well, but I can't think of which off the top of my head. Also, for some reason my question's title was lost after clicking the back button, so that was doubly annoying.
Could we just dump users back at the question/whatever page with the "you can only submit questions ever 60 seconds" error appearing as an inline validation message instead? It might also help save me from the dreaded insta-captcha after submitting again.